exocortex

An external cognitive layer: a shared long-term memory for you and your agents, built on a plain-markdown vault you own outright.

Design in one line: markdown in git is the source of truth; the index, hybrid search, graph, agents, and 3D visualization are all derived layers you can delete and rebuild. No lock-in, no black box, no single SaaS to trust.

See docs/ARCHITECTURE.md for the full reasoning. Quickstart below.

Provenance: this is the real system I run daily, extracted as-is — my private vault (a few hundred notes) is swapped for a 4-note demo vault, and personal endpoints are example.com placeholders. Everything else — CLI, MCP server, the bird agents, the gardener, hooks, eval harness — is exactly the code that tends my memory every night.

The fleet — every moving part at a glance

The system is one vault plus a handful of small, single-purpose programs. Nothing here is magic; each one is a script or a hook you can read.

The one rule that ties it together — trust boundaries by destination: gardener and wanderer read already-trusted notes and write to vault/ and push to main. The three corvids — Magpie, Bluejay, Jackdaw — ingest attacker-influenceable text (stranger-written repo descriptions, RSS summaries, contributor profiles), so they write only to quarantine/ (never indexed, never auto-linked) and you promote finds by hand. Their collide/classify phase holds the untrusted text in context with no Bash, no git, no network, no MCP — read the vault, write one quarantine file, nothing else — and the wrapper discards any change outside that path. "Nothing sparked" is a successful run; the birds never manufacture a find to look productive. The WIP sweep writes unfinished human work to wip/<host> branches — recoverable, but it reaches main only by your hand. Robot checkouts (exocortex-{garden,wander,magpie}) hard-reset every run, so they self-heal and never strand work.

Related MCP server: Obsidian MCP Server

What you get

• Vault (vault/) — typed markdown notes, wikilinks, typed relations.

• Hybrid retrieval — BM25 + local vectors + graph expansion, with matched_on explainability. One SQLite file; no extra servers.

• Two MCP servers for agents:

  • Basic Memory — note CRUD (adopted, not reinvented).

  • exocortex (this repo) — hybrid_search, get_backlinks, get_neighbors, list_orphans, list_hubs, garden_report, reindex, vault_status, collide.

• Collision engine — exo collide samples distant note pairs (graph hops, lexical disjointness, age gap) and asks one question: does anything connect? Serendipity as a query — retrieval answers, collide interrupts. Most pairs yield nothing by design; genuine hits land in vault/00-inbox/claude-sparks.md.

• Reconciler — GitOps for the index: exo status reports Synced/OutOfSync (exit 0/1) by hashing vault files against the index, and .githooks/ (post-commit + post-merge) reindexes automatically. "Files win" is enforced by a machine, not remembered by agents.

• Autonomous gardener — exo garden deterministically finds orphans, stale summaries, and missing links; Claude acts on them as small, reviewable garden: git commits (it decides + writes, the detection is plain SQL/graph). Runs unattended nightly on the homelab — see "Nightly self-gardening" below.

• Visualization — Obsidian 2D + 3D Graph plugin, plus a standalone 3d-force-graph web viewer (viz/graph3d/) deployable to the homelab.

• Automation — scripts/garden-run.sh (the nightly gardener) + an n8n webhook that records each run.

• Homelab deploy — Dockerfile + k3s manifests (Traefik IngressRoute) + Argo CD app.

Install (local)

git clone <this> exocortex && cd exocortex
./scripts/setup.sh            # installs, git-inits, builds the index
# optional local embeddings via Ollama:
ollama pull nomic-embed-text  # then EXO_EMBED_BACKEND=ollama (default)

No Ollama? Set EXO_EMBED_BACKEND=none — lexical + graph search still work fully.

MCP wiring (Claude Code / Desktop)

{
  "mcpServers": {
    "basic_memory": { "command": "uvx", "args": ["basic-memory", "mcp"] },
    "exocortex":    { "command": "exo-mcp" }
  }
}

Point Basic Memory at vault/. Load CLAUDE.md as the agent's operating contract.

Quickstart

exo index                      # (re)build the index from markdown
exo search "hybrid retrieval"  # explainable hybrid search
exo backlinks hybrid-retrieval
exo hubs                       # most-connected notes (MOC candidates)
exo garden                     # maintenance report for an agent to act on
(cd viz/graph3d && python3 -m http.server 8080)   # 3D brain at :8080

Layout

vault/      the knowledge base (open this in Obsidian)
src/exo/    the cognition layer (indexer, retrieval, graph, gardener, MCP, CLI)
viz/        standalone 3D viewer
automation/ n8n workflows
deploy/     Dockerfile + k3s + Argo CD for tc-homelab
docs/       ARCHITECTURE · ONTOLOGY · WORKFLOWS · ROADMAP
CLAUDE.md   agent operating contract

Nightly self-gardening (homelab)

The vault weeds itself. A node-side cron runs scripts/garden-run.sh nightly:

reset a disposable checkout → exo index → exo garden (deterministic report)
  → claude -p applies only high-confidence edits (≤10 notes), writes a dated
    audit note to vault/00-inbox/, skips anything uncertain
  → exo index → one `garden: <date> …` commit → push
  → POST a run summary to an n8n webhook (run history / notifications)

Design choices that keep it safe: a dedicated checkout (never touches your working tree), a per-night edit cap, hermetic Claude (no MCP, restricted tools), and — crucially — every change is one garden: commit you can read with git log -p and undo with git revert. Detection is deterministic; the model only decides and writes. (The trigger is node-cron rather than n8n-over-SSH because Cilium blocks pod→host — see the blog write-up.)

Why this and not X

• vs Obsidian-alone: Obsidian can't give agents structured read/write or hybrid retrieval. Here it's the viewer; the store is portable markdown.

• vs embeddings-only RAG: opaque and can't write back. This is transparent (every match explains itself) and bidirectional (agents author notes).

• vs a graph DB (Neo4j): unnecessary infra. The graph lives in wikilinks; SQLite materializes it. Add a graph DB only if/when queries outgrow this.

• vs cloud knowledge SaaS: lock-in. Here, git clone is your backup and any markdown tool is your fallback.